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Clean Air Status and Trends - Ozone

This demo shows a map of the U.S. depicting the Clean Air Status and Trends Network (CASTNET) Ozone monitoring stations and their average Ozone level. Clicking a station shows more detailed information and a link to a graphical representation of the time-series of measurements.

About

For this demo, we used RDF data derived from ozone and visibility readings provided by the EPA's Castnet project. This RDF combines raw data on Castnet readings (ozone and visibility) with corresponding geographic information on the sites of readings, which the raw Castnet data lacks. On the provided map of the US, every yellow dot represents a single Casetnet site and dot size corresponds to an average Ozone reading for that site, where larger dots represent larger averages. When a Castnet site is clicked, a small pop-up opens, displaying more information on that site, along with a link. This link takes the user to another page that displays in a timeline all the Ozone and Visibility data available for that site. This timeline uses the Google Visualization API giving users added functionality in how they view the data in the timeline. To allow users to filter through Castnet readings, a faceted browsing interface (from the MIT Simile Exhibit API) is provided.

Interesting observations

This demo uses SPARQL to combine raw data on the Castnet Project (dataset 8) from Data.gov and geographic information on Castnet Stations (Dataset 10001) from the EPA website. This enables the demo to plot Castnet readings on a US map, allowing users to look for geographic relationships within the Castnet data. When a user clicks on a Castnet station, historical ozone values for that station can then be viewed through a timeline. Finally, the use of faceted browsing aids users in interacting with presented data, allowing for filtering based on different criteria.

Technology Highlights

This uses the RDF to Google visualization conversion process of using a SPARQL service and XSLT to put the data in JSON format.

SPARQL is used to grab data from two datasets.

This also uses MIT Simile Labs Exhibit to make the faceted browsing map.

A Web service is used to convert JSON from SPARQL into JSON that Exhibit can use.

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